This invention relates to a vehicular mounted plow for clearing snow or the like and, in particular, to a locking mechanism for automatically engaging an angularly adjustable blade mechanism when the mechanism is placed in a working or snow removal position and for releasing the blade when the assembly is lifted from the working position.
The most pertinent prior art known to the applicant at the time of filing this application is contained in the following U.S. Pat. Nos.:
1,195,271 PA1 2,251,452 PA1 2,792,656 PA1 2,854,766 PA1 3,012,345 PA1 3,353,287
As described by Kruger in the above-noted U.S. Pat. No. 3,012,345, many vehicular driven snowplows are equipped with locking devices for securing the blade mechanism of the plow at some desired angular position relative to the longitudinal axis of advance of the blade as typically described by the forward motion of the vehicle. Conventionally, the locking device is controlled by a hydraulic cylinder which serves to selectively position a reciprocating locking pin into one of a plurality of receiving holes formed in the main support frame of the plow assembly. It sometimes becomes difficult for the operator, who is remotely situated in the cab of the vehicle, to properly seat the locking pin in the appropriate receiving hole. When improperly aligned, the pin can be clamped against the top surface of the sector plate, rather than being seated in one of the receiving holes, thereby providing only a minimum amount of holding force against the blade. As a consequence, the blade, upon coming in contact with a relatively large mass of snow, may be rapidly rotated about the support frame of the plow thereby creating a potentially dangerous situation.
In operation, most snowplow blades are initially lifted in a vertical direction some distance above the roadbed before the blade is angularly moved to a new working position. Typically, the lifting, repositioning, and blade locking functions are individually controlled, thus requiring that the operator perform the operations in an ordered sequence in order to avoid damaging the equipment. For example, if the lifted blade is angularly repositioned before the locking pin is removed, the pin will usually be bent and/or the hydraulic system damaged thereby rendering the plow inoperative.